A police officer walks past a plaque of the oil firm TNK-BP at its headquarters in Moscow. Photograph: Sergei Karpukhin/Reuters

In the opaque world of Vladimir Putin's Russia, business and politics are invariably linked. Especially when the business in question is Russian oil and gas, the source of modern Moscow's global influence and geopolitical might.

It's possible, of course, to read the announcement that BP may sell its 50% stake in its Russian joint venture TNK-BP as a purely corporate decision. BP has, after all, been at war with its powerful oligarch partners for more than five years.

The battle has been long, acrimonious and at times surreal. TNK-BP's chief executive, Bob Dudley, was hounded out of Russia in 2008 after his visa wasn't renewed; Moscow police raided BP's offices; Mikhail Fridman, the smooth frontman for BP's Russian partners, accused BP of spreading "Goebbels-like propaganda". "It was impossible to know what was going on. Or why," one former employee said of the bloody period.

And yet sources say a Russian state oil and gas group is about to buy out BP. The group's identity is unknown but it is most likely to be Gazprom or Rosneft. Both are powerful, state-owned behemoths. It is inconceivable their "unsolicited" approach for BP's share could take place without approval at the top of the Kremlin – the very top.

The move comes weeks after Putin's return for a third stint as Russia's president. Despite attempts by David Cameron to improve relations, Britain is still one of the Kremlin's least loved EU partners.

On Wednesday it emerged that Putin will not be at the London Olympics – a snub. He remains unforgiving of Britain's refusal to extradite critics such as Boris Berezovsky and is furious at the looming threat of visa bans for Russian officials who abuse human rights.

BP may get $25bn (£16bn) for its share, a good price that would satisfy investors. The argument, then, would be that BP's involuntary exit from Russia was not a disaster.

But it seems no coincidence that BP is going at a time of poor bilateral relations.

It wasn't always like this: few remember that Putin's first foreign visit as president in 2000 was to London, where he was hailed by Tony Blair as a fellow reformer. TNK-BP was founded three years later. Almost a decade on, the partnership is at an end and Britain is left in the cold.